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M G. T. WOODS.

TELEPHONE TRANSMITTER.

No. 308,817. Patented Dec. 2, 1884.

11. PETERS. Phalo-Lnlhcgrz-phur, Washington. n. z;

Nirnn STATES GRANVILLE T. \VOODS, OF CINCINNATI, OHIO, ASSIGNOR OF TlVO- THIBDS TO LEVIS M. I-IOSEA AND DAVID HUMPHREYS, BOTH OF SAME PLACE.

TELEPHONE-TRANSMITTER.

iPEQIFlEQAIEQN forming part of Letters Patent No. 308,817, dated December 2, 1884:.

Application filed June 18, 1883.

T aZZ whom it may concern:

Be it known that I, GRANVILLE T. W'OODS, a citizen of the United States, residing at Cincinnati, Ohio, have invented new and useful Improvements in Telephone-Transmitters, of which the following is a specification.

My invention relates to the transmission of sound by means of the electric current; and it consists in the means,hereinafter described, for producing and utilizing alternate currents for this purpose, controlled by the action of vibrating diaphragms.

The object of my invention is to produce more distinct and powerful effects than are attained by the undulatory current ordi-- narily employed in telephonicapparatus, and capable of transmission to longer distances; and this I accomplish by alternating the current, bymeans of varying pressure, upon two or more carbon or other semi-conductors,produced by the action of the diaphragm, set in motion by vocal or other impulses, arranged as hereinafter more fully described and illustrated.

The drawing shows'a sectional elevation of a transmitter employing two diaphragms, two carbon conductors, two batteries,and an in ductioncoil operating the line-wire by reversed currents.

The apparatus consists of a box having a sound-receiving bell or mouth -piece, A,

two diaphragms, B B, preferably conductors of electricity, and two carbon points, U G, mounted upon spring-standards c o provided with adjusting-screws c c, for regulating the pressure of the carbons against the diaphragms. Connections are made between the diaphragms and batteries, and also between the standards and batteries, these connections passing through the primary circuit of an induction coil, D, as hereinafter described, whose secondary circuit is in the line L L.

The operation is as follows: A vocal impulse delivered atA presses both diaphragms outward in opposite directions, thus compressing carbon O, increasing its conductingpower, and at the same time relieving the (No model.)

equilibrium is destroyed, and battery E is brought into controlling action, its current passing over wire 4, standard 0, carbon C, diaphragm B, wire 6, through the primary coil from left to right, and thence over wire to battery. An impulse in the opposite direction, actuating the diaphragms against car- 'bon O and from carbon 0, would establish the current through the former, in which event the current flows from battery E over wire 1, diaphragm B, carbon C, standard 0, wire 3, through primary coil of D from right to left, and thence over wire 2 to battery. The reversal of the current in the induction-coil also produces a reversal in the linecurrents, which, acting uponthe eleetromagnet of the receiving-instrument, attracts and repels the diaphragm with a wide range of movement, producing a large volume of sound. On a short line the induction-coil may be dispensed with and direct-line currents used.

I claim as my invention and desire to secure by Letters Patent 1. In a telephone-transmitter, the combination of two diaphragms arranged with a space between them,'a mouth-piece communicating with said space, carbons or similar conductors arranged relatively thereto, substantially as described, so that one shall be compressed and the other relieved from pressure by the simultaneous vibration of the diaphragms, and connections, substantially as described, leading from said carbons to the line.

2. The combination of two diaphragms arranged with a space between them, as de scribed, a mouth-piece communicating with said space, carbons arranged, as described, so that one shall be compressed and the other relieved from pressure by the simultaneous vibration of the-diaphragn1s, electric connecmy hand in the presence of two subscribing tions from the diaphragnis to batteries, and witnesses. electric connections from the carbons to batteries through the primary of an induction- 5 coil and connections from said coil to line, sub- Witnesses:

v stantially as described.

In testimony whereof I have hereunto set GRANVILLE T. WVOODS.

L. M. I-IOSEA, ALEX. HAMILTON. 

